Medical Interventions Unit 3

CT Scan

CT rules

• bone is white

• less dense tissue and fluids are dark

• table or brace may be visible

MRI rules

• bone is black

• less dense tissue and fluids are light

• no table or brace is visible

Hyperplasia

increase in number of cells

CT scans are created by

x-rays, formed from cross-sectional “slices”; creates a 3D image

CT scans are used for

organs, soft tissue blood, blood vessels

MRI

MRIs are created with

magnets and radio waves; no radiation

MRI’s are used for

diagnose soft tissue issues, joints, tendons, ligaments

• muscles

• brain

X-ray

X-rays are created by

electromagnetic radiation; 2-D image

X-rays are used for

dense tissue: bone

bone scan

bone scans are used for

whole body scan to determine bone metabolism and cancer metastasis

bone scans are created by

radioactive substances injected and rate of uptake in this tissues is imaged

sarcomas

• cancer that affects the bone and soft tissues (connective tissue)

• can affect fat, bone, and muscle

• arise in cells supporting tissue (ex: bone, cartilage, fat)

carcinomas

• cancer in cells that make up lining of organs (epithelia)

• can affect breast, skin, colon, lung, prostate, and bladder

• arise from cells that cover external/internal surfaces

lymphomas

cancer that begins in cells of the immune system, lymphocytes (t cells or b cells)

leukemia

• cancer in the bloodstream/bone marrow

• doesn’t form solid tumors

apoptosis

programmed cell death

cancer

disorder in which some of the body’s cells lose the ability to control growth

mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

cell cycle checkpoints

points of transition between different phases of the cell cycle that are regulated; checks for errors occur

dysplasia

• abnormal growth and development of cells and tissue

• considered precancerous

metastasis

cancer cells penetrate into lymphatic/blood vessels and circulate in bloodstream

benign tumors

• non cancerous

• slow growing

• can’t spread

malignant tumors

• cancerous

• fast growing

• can spread by invasion or metastasis

angiogenesis

• when new blood vessels are formed from existing one

• cancer cells stimulate to “feed” tumors

cancer cell characteristic

• irregularly shaped dividing cells

• large, weird nucleus

• disorganized arrangement

• variation in cell size/shape

oncogenes

genes that have potential to cause a normal cell to become cancerous

proto-oncogenes

• a gene involved in normal cell growth

• mutations in proto-oncogenes may cause it to become an oncogene

tumor suppressor genes

genes that slow down cell division, repair DNA mistakes, or tell cells when to die (apoptosis)

• absence can lead to cancer

• brake pedal of cell growth

p53

• “guardian of geneome”

• activates genes that stop cell growth or cause cells to die when cell has damaged DNA

• involved with cell cycle checkpoints

• tumor suppressor

replicate senescense

• normal cells have a limited capacity for replication

• fixed number of times they can undergo mitosis.

contact inhibition

normal cells stop replicating when they hit a barrier

how do we know if a gene is “turned on”?

it is transcribing mRNA

what are in the wells on a DNA Microarray?

each well has strands of DNA for a specific gene of interest

DNA Microarray

• extract RNA from samples

• add labeling mix: will create a complimentary DNA strand for each RNA molecule (using reverse transcriptase and a primer); green and red fluorescent markers added

• wash over microarray; DNA and cDNA will bind

• lasers reveal microarray colors

cDNA

• complimentary DNA

• obtained from healthy and cancerous tissue

• has fluorescent labels that allows us to visualize it (green = healthy, red = cancer)

yellow spots on microarray

gene hybridized to both green and red cDNA

• equally transcribed in both cancer and normal tissue

red spot on microarray

genes that produce more mRNA in cancer cells (up-regulated in cancer)

green spots on microarray

genes that produce more mRNA in healthy cells (down-regulated in cancer)

black spots in microarray

gene not transcribed in the healthy cell or cancer cell

when microarray ratio is > 1

gene is induced by tumor formation

when microarray ratio is < 1

gene is suppressed by cancer cells

when microarray ratio = 1

expressed in both cells (not important to research)

when microarray ratio = 0

not expressed in either cell

when base 2 log is positive

up-regulated in cancer

when base 2 log is negative

down-regulated in cancer

when base 2 log is = 1

not affected by tumor formation

when PCC is positive

gene profiles behave similarly; larger = stronger correlation

when PCC is negative

gene profiles behave in opposite waves; larger = more opposite

when PCC is 1

gene expression is identical

when PCC is 0

unrelated gene expression

dendrogram

treelike diagram used to display results; used to link gene expressions that are closely related

correlation

a measure of the relationship between two variables

ex: genes and treatments

risk factors for cancer

• alcohol

• obesity

• smoking

• genetics

• age